Climate is a major driver of pest distribution and it is expected that changing climate will alter historic patterns of pest outbreaks. The Australian plague locust (Chortoicetes terminifera; APL) is the most economically important locust species in Australia. Understanding its large-scale and long-term dynamics is a prerequisite to develop effective control and preventive management strategies to mitigate damage for crops and pastures. We used a 32-year locust survey data set to identify relationships between climate and spatiotemporal dynamics of seasonal outbreaks and develop species distribution models (SDMs). These models were then projected into a future climate change scenario (RCP8.5) using 34 global climate models (GCMs) to assess how climate change may alter APL specific distribution patterns in eastern Australia.
Results/Conclusions
Our results show that two SDMs predicted the spatial distribution of APL outbreak well based on the evaluation criteria. Overall, the model performed better for spring outbreaks than summer and autumn. We ranked the importance of explanatory variables and demonstrated the partial effect of two most importance variables on the spatial distribution of APL outbreak. Spring outbreaks are mainly influenced by precipitation seasonality and mean temperature of coldest quarter. Summer outbreaks are mainly influenced by mean temperature of driest quarter and mean diurnal range. Autumn outbreaks were mainly influenced by high rainfall in the driest quarter and high temperature.
Our modelling predicted that APL outbreak areas are likely to decrease regardless of seasons due to changing climate. Multi-GCMs ensemble means showed that the largest decrease of outbreak areas was in spring (93-94% by 2081-2090). The spatial distribution of future APL outbreaks presented different season-specific patterns. Our selected bioclimatic variables explained 78-98% of outbreak area change. This study represents an important step towards the assessment of the effects of changing climate on a locust species outbreaks and can help inform future priorities for regional mitigation effort in the context of climate change.